Carcinogenicity test of 50 Hz sinusoidal magnetic fields in rats

Male and female F344 rats, 48 per exposure group, were sham exposed (Group A) or exposed to 0.5 (Group B) and 5 mT (Group C) magnetic fields for two years. Animals were exposed from 5–109 weeks of age in SPF conditions according to the OECD test guideline No. 451. Average exposure was 22.6 hr/day. No significant differences in body weight and food consumption were observed between the sham and exposed groups. At the end of the exposure period, survival rates of the male rats were 73, 83, and 79%, and those of the females, 77, 79, and 75% for Groups A, B, and C, respectively, with no significant differences between groups. Differential counts of leukocytes were measured at the 52nd, 78th, and 104th weeks of exposure and no significant differences were observed between the exposure groups. All survivors were euthanized on schedule, and all the organs and tissues suspected of tumoral lesions were examined histopathologically. Incidences of mononuclear cell leukemia in the male and the female rats were 5, 4, 4 and 8, 6, 7 for Groups A, B and C, respectively; incidences of malignant lymphoma in the female rats were 0, 1 and 1. Neither significant increases nor acceleration of incidence of leukemia were observed. Incidences of brain and intracranial tumors did not increase in the exposed groups. Incidences of both benign and malignant neoplasms showed no significant difference between the exposed and sham exposed groups with one exception: fibroma of the subcutis in the male rats, which was considered not to be a statistically significant when evaluated with respect to the historical control data in our laboratory. Bioelectromagnetics 18:531–540, 1997. © Wiley-Liss, Inc.     

Effects of 900 MHz GSM wireless communication signals on DMBA-induced mammary tumors in rats

The purpose of the study was to investigate whether exposure to 900 MHz GSM wireless communication signals enhances mammary tumor development and growth induced by low-dose DMBA. Five hundred female Sprague-Dawley rats were treated with a single dose of 35 mg/kg DMBA and then divided into five groups in a blinded fashion: one cage control group and four exposure groups, including three microwave exposure groups and one sham exposure with specific absorption rates (SARs) of 4.0, 1.33, 0.44 and 0 W/kg, respectively. Exposure started on the day after DMBA administration and lasted 4 h/day, 5 days/week for 26 weeks. Rats were weighed and palpated weekly for the presence of tumors and were killed humanely at the end of the 26-week exposure period. All mammary glands were examined histologically. There were no statistically significant differences in body weight between sham- and GSM microwave-exposed groups. No significant differences in overall mammary tumor incidence, latency to tumor onset, tumor multiplicity, or tumor size were observed between microwave- and sham-exposed groups. There was a tendency for reduction of mammary adenocarcinoma incidence in the lowest microwave exposure group (0.44 W/ kg) compared with the sham-exposed group (P = 0.058). Additionally, a higher incidence of adenocarcinoma was noticed in the 4.0 W/kg group from the 15th to 26th weeks, especially in the 19th week (P = 0.358 compared to sham). However, neither tendency was statistically significant; thus this study does not provide evidence that GSM microwave exposure promotes mammary tumor development in rats. In the present study there were significant differences between the cage controls and the experimental groups (sham and exposure). Body weight and mammary tumor (malignant plus benign) incidence in the cage control group were significantly higher than in the sham- and GSM microwave-exposed groups. The latency to the mammary tumor onset was significantly shorter in the cage control group than in the other groups.     

Power-frequency magnetic fields at 50 Hz do not affect fertility and development in rats and mice

In the present study, the effects of power-frequency magnetic fields (PF-MF) on fertility and development were investigated in rats and mice. Adult Sprague-Dawley rats and C57BL/6J mice were divided into four groups: a sham exposure group and 30-µT, 100-µT and 500-µT PF-MF exposure groups. The rats were exposed for 24 weeks, and the exposure time for mice ranged from 18 d to 12 weeks, dependent on the different investigated end points. The rats and mice were exposed for 20 h/d. Plasma hormone levels in rats and mice were analyzed. Furthermore, pregnancy rates and implanted embryos were recorded in pregnant mice. Finally, the neonatal growth of mice was evaluated. The results showed that none of the three intensities affected the body weight and paired ovary weight in female rats. Meanwhile, none of the three intensities affected the body weight, weights of paired testes, weights of paired epididymis and sperm count in male rats. Similarly, no significant differences were found in plasma sex hormone levels between the different PF-MF exposure groups and the sham exposure group. In addition, the pregnancy rates and implanted embryos were not significantly different between the four groups. Moreover, PF-MF exposures had no effects on either the number of fetuses in pregnant mice or the growth and development of neonatal mice.     

Effects of feminization of male F344 rats on induction of tumors and on nucleic acid alkylation by nitrosobis-(2-oxopropyl)amine

Groups of male and female F344 rats were treated twice weekly by gavage with 2.5 mg of nitrosobis-(2-oxopropyl)amine (BOP) for 35 weeks. Additional groups given the same treatment were male rats castrated at birth, male rats bearing an implant of a pellet containing estradiol and castrated male rats bearing an estradiol pellet. Most rats died with tumors related to the treatment; intact male rats survived the least well of the five groups. Most rats in all groups had alveolar/bronchiolar neoplasms of the lung. Many of the male rats also had follicular cell neoplasms of the thyroid and transitional cell neoplasms of the urinary bladder and kidney pelvis; there were no liver tumors in intact male rats. Almost all female rats and castrated male rats had liver neoplasms, including hepatocellular, cholangiocellular and hemangiosarcomatous neoplasms, but few neoplasms of the thyroid, kidney or bladder. The male rats feminized with estradiol, intact or castrated, had liver neoplasms, mainly cholangiocellular, and also neoplasms of the thyroid. Two rats of each of the five groups were treated at 20 weeks of age with [14C]BOP. As measured by respiration of 14CO2, metabolism of BOP was faster in the two groups of male rats with the estradiol implant than in the other groups. DNA and RNA of the liver were isolated 6 h after treatment. The extent of methylation of liver DNA as 7-methylguanine and O6-methylguanine was higher in the females and in the feminized males than in the intact male rats, but when normalized to the dose of nitrosamine per unit body weight there was little difference among the five groups.     

袖状胃切除术Wistar大鼠模型建立及初步观察

目的探讨袖带胃切除术对Wistar大鼠体质量、大鼠前胃黏膜及黏膜肌层厚度的影响,为进一步研究袖状胃切除术的减重机制提供形态学依据。方法 20只雄性Wistar大鼠被随机分为2组,12只行袖状胃切除术做为手术组;8只行胃干预组做为假手术组,术前、术后第1天及术后1月内每周,而后每两周进行体重测量,术后12周处死大鼠后制作前胃石蜡切片,组织学方法观察其形态变化。结果手术组大鼠存活10只,成活率83%。假手术组大鼠在术后增重明显,手术组大鼠体重在术后2周恢复术前水平,体重增长明显但较假手术组慢（P〈0.05）。手术组大鼠术后前胃有代偿性扩张,光镜下可见黏膜及黏膜肌层厚度变薄,黏膜皱襞变浅。结论袖状胃切除术大鼠模型中对前胃的形态学观察可能有利于进一步阐明该术式大鼠模型的减重和体重反弹机制。     

Carcinogenicity study of GSM and DCS wireless communication signals in B6C3F1 mice

The purpose of this study using a total of 1170 B6C3F1 mice was to detect and evaluate possible carcinogenic effects in mice exposed to radio-frequency-radiation (RFR) from Global System for Mobile Communication (GSM) and Digital Personal Communications System (DCS) handsets as emitted by handsets operating in the center of the communication band, that is, at 902 MHz (GSM) and 1747 MHz (DCS). Restrained mice were exposed for 2 h per day, 5 days per week over a period of 2 years to three different whole-body averaged specific absorption rate (SAR) levels of 0.4, 1.3, 4.0 mW/g bw (SAR), or were sham exposed. Regarding the organ-related tumor incidence, pairwise Fisher's test did not show any significant increase in the incidence of any particular tumor type in the RF exposed groups as compared to the sham exposed group. Interestingly, while the incidences of hepatocellular carcinomas were similar in EMF and sham exposed groups, in both studies the incidences of liver adenomas in males decreased with increasing dose levels; the incidences in the high dose groups were statistically significantly different from those in the sham exposed groups. Comparison to published tumor rates in untreated mice revealed that the observed tumor rates were within the range of historical control data. In conclusion, the present study produced no evidence that the exposure of male and female B6C3F1 mice to wireless GSM and DCS radio frequency signals at a whole body absorption rate of up to 4.0 W/kg resulted in any adverse health effect or had any cumulative influence on the incidence or severity of neoplastic and non-neoplastic background lesions, and thus the study did not provide any evidence of RF possessing a carcinogenic potential.     

二月桂酸二丁基锡对大鼠妊娠及对子代毒性作用

目的通过染毒观察二月桂酸二丁基锡（Dibulytin Dilaurate,简称DBTD）对子代胎鼠形态、体重、性别及骨骼发育状的影响。方法按随机分组的原则,将大鼠分为对照组和染毒组,对照组用玉米油,染毒组用DBTD玉米油溶液,浓度分别是2.5 mg/kg体重（1/72 LD50）、10 mg/kg体重（1/18 LD50）和20 mg/kg体重（1/9 LD50）,采用灌胃的方式进行染毒,6 d/周,每天同一时间进行染毒,共计染毒48 d。染毒第五周后,各组大鼠与正常雄性大鼠以1：1的比例合笼,合笼期间不染毒,每只雌鼠查到阴栓为妊娠第0天,继续染毒,于妊娠第18天处死取胎鼠。结果1/18 LD50及1/9LD50剂量组中活胎及胎儿的体重明显下降,1/18 LD50剂量组胎儿的性别开始发生明显的变化（P〈0.05）。结论DBTD染毒对大鼠每胎存活数、胎重、胎儿的形态及性别有影响,有一定的生殖毒性。     

不同周龄SD大鼠脏器重量及其变化趋势分析

目的分析不同周龄SD大鼠的脏器重量及其变化趋势,为评判药物毒性反应提供理论参考。方法分别选取试验第13、26、52、78和104周对照组动物脑、脾脏、心脏、肺脏、肝脏、肾脏、肾上腺、睾丸、卵巢的重量数据并分析。结果从13～104周SD雌鼠脑、脾脏、心脏、肺脏、肝脏、肾脏、肾上腺、卵巢的重量呈升高趋势。从13～104周SD雄鼠脑、脾脏、心脏、肺脏、肝脏、肾脏重量均重于雌鼠,但雌鼠肾上腺重量、脏体比和脏脑比均显著高于雄鼠。结论本研究首次在国内建立了符合我国实验动物现状的,不同周龄SD大鼠的脏器重量背景数据和参考值范围,并分析了不同周龄SD大鼠脏器重量变化趋势。     

Balloon expansion of the pectoralis major muscle flap in sternoplasty: a biomechanical and histologic study in a rat model

The pectoralis major advancement flap is currently the most popular technique for reconstruction of the anterior chest in patients with sternotomy wounds. Recently, the SpaceMaker balloon was introduced for rapid expansion of the pectoralis major muscle intraoperatively. The aim of the present study was to investigate the biomechanical and histologic effects of this expansion technique in a rat model. The upper 2 cm of the sternum was resected in 54 male rats. Reconstruction with balloon-assisted pectoralis muscle expansion was performed in 24 rats (study group). Another 24 rats underwent reconstruction with simple muscle advancement without expansion. Submuscular insertion of a catheter for expansion, without inflation, was performed in the remaining six rats (sham group). Rats were killed either immediately or 2 to 4 weeks after surgery. Thirty-eight rats, including 16 after reconstruction with expansion, 16 after reconstruction without expansion, and six in the sham group, were killed immediately after surgery. Sixteen rats were killed 2 to 4 weeks after surgery, eight rats for each reconstruction technique. Before the animals were killed, the biomechanical properties of the muscles were tested with weights to calculate stiffness (in newtons per meter) and compliance gain (in percent). After the animals were killed, biopsy specimens were obtained for histologic analysis. Results indicated significantly lower muscle stiffness in the study group compared with the others immediately after surgery (p = 0.0000), although the difference failed to achieve statistical significance 2 to 4 weeks later (p = 0.76). In the study group, the compliance gain was 74.4 percent immediately after surgery but only 3.4 percent 2 weeks to 1 month postoperatively. Histologic examinations in all groups immediately and 2 to 4 weeks after surgery revealed regular muscle striation with no signs of inflammation. The elastic stiffness of the rat pectoralis major muscle is significantly reduced following rapid intraoperative expansion and returns to normal 2 to 4 weeks later.     

去卵巢大鼠血清和骨髓细胞碱性磷酸酶水平变化的动态观察

目的：动态观察去卵巢大鼠血清和骨髓细胞碱性磷酸酶（ ALP）水平的变化。方法将80只3月龄雌性SD大鼠按体重分层后随机分为基础组以及假手术和去卵巢3、6、12、24周组。分别在手术前（0）和手术后3、6、12、24周腹主动脉取血处死各组大鼠,分离血清,制备骨髓细胞甩片,用721分光光度计检测血清ALP水平的变化;用显微镜计数骨髓细胞甩片ALP阳性染色细胞的数目。结果在假手术组大鼠中,血清ALP水平在手术后3周显著上升并持续到手术后6周,但在手术后12周开始显著下降并持续到手术后24周;骨髓细胞ALP阳性染色细胞数目在手术后3周显著上升并持续到手术后12周,但在手术后24周却显著下降。在去卵巢组大鼠中,血清ALP水平在手术后3周显著上升,到手术后6周开始显著下降并一直持续到手术后24周;骨髓细胞ALP阳性染色细胞数目在手术后3周显著下降并持续到手术后24周。从手术后3周开始,去卵巢组大鼠血清ALP水平均显著高于假手术组大鼠,但骨髓细胞ALP阳性染色细胞数目均显著低于假手术组大鼠。结论假手术组大鼠血清和骨髓细胞ALP水平变化趋势基本相似,但去卵巢大鼠血清和骨髓细胞ALP水平变化趋势不同。     

No effects of radiofrequency radiation on 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone-induced tumorigenesis in female Wistar rats

This study evaluated possible effects of radiofrequency (RF) radiation on tumorigenesis induced by the mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) given in drinking water. Female Wistar rats aged 7 weeks at the beginning of the experiments were randomly divided into four groups of 72 animals: a cage-control group and three MX-exposed groups (a daily average dose of 1.7 mg MX/kg body weight for 104 weeks), of which two were exposed to 900 MHz pulsed RF radiation and the third served as a sham-RF-radiation group. The RF-radiation groups were exposed 2 h per day, 5 days per week for 104 weeks at nominal whole-body average SARs of 0.3 W/kg and 0.9 W/kg. Complete histopathology was performed on the rats of the three MX-exposed groups. The tumor types and incidences observed in the MX-exposed animals were similar to those reported earlier in MX-exposed female Wistar rats. RF radiation did not statistically significantly affect mortality or organ-specific incidence of any tumor type. The only statistically significant difference was an increase in the combined frequency of vascular tumors of the mesenteric lymph nodes in the high-RF-radiation group compared to the sham-RF-radiation group. However, additional histopathological analysis of the cage-control animals suggested that this difference was due to unusually low frequency of this type of tumor in the sham-RF-radiation group rather than a high frequency in the high-RF-radiation group. With respect to non-neoplastic findings, statistically significant differences between the RF-radiation groups and the sham-RF-radiation group were observed only for single findings in the lacrimal glands, lungs, liver and skin. Such changes are commonly seen in aged rats and were considered to be unrelated to RF radiation. The results of the present study do not support co-carcinogenic effects of low-level long-term RF-radiation exposure in rats.     

The effect of chronic exposure to 835.62 MHz FDMA or 847.74 MHz CDMA radiofrequency radiation on the incidence of spontaneous tumors in rats

This study was designed to determine whether chronic exposure to radiofrequency (RF) radiation from cellular phones increased the incidence of spontaneous tumors in F344 rats. Eighty male and 80 female rats were randomly placed in each of three irradiation groups. The sham group received no irradiation; the Frequency Division Multiple Access (FDMA) group was exposed to 835.62 MHz FDMA RF radiation; and the Code Division Multiple Access (CDMA) group was exposed to 847.74 MHz CDMA RF radiation. Rats were irradiated 4 h per day, 5 days per week over 2 years. The nominal time-averaged specific absorption rate (SAR) in the brain for the irradiated animals was 0.85 +/- 0.34 W/kg (mean +/- SD) per time-averaged watt of antenna power. Antennas were driven with a time-averaged power of 1.50 +/- 0.25 W (range). That is, the nominal time-averaged brain SAR was 1.3 +/- 0.5 W/kg (mean +/- SD). This number was an average from several measurement locations inside the brain, and it takes into account changes in animal weight and head position during irradiation. All major organs were evaluated grossly and histologically. The number of tumors, tumor types and incidence of hyperplasia for each organ were recorded. There were no significant differences among final body weights or survival days for either males or females in any group. No significant differences were found between treated and sham-exposed animals for any tumor in any organ. We conclude that chronic exposure to 835.62 MHz FDMA or 847.74 MHz CDMA RF radiation had no significant effect on the incidence of spontaneous tumors in F344 rats.     

The effects of pulsed 860 MHz radiofrequency radiation on the promotion of neurogenic tumors in rats

In a previous study, this laboratory reported a statistically nonsignificant trend for shortened latency of ethylnitrosourea (ENU)-induced brain tumors in Sprague-Dawley rats exposed to an 860 MHz pulsed radiofrequency (RF) signal. The present study was designed to investigate further any promoting effect of the pulsed RF signal on latency and other characteristics of neurogenic tumors in the progeny of pregnant rats treated with 6.25 or 10 mg/kg ENU. The resulting 1080 offspring were randomized equally by number, sex and ENU dose into pulsed RF, sham and cage control groups. The rats were exposed to the pulsed RF signal 6 h per day 5 days per week; the sham-exposed group was similarly confined for the same periods, and the cage controls were housed in standard cages. An essentially equal number of rats from each group were killed humanely every 30 days between the ages of 171 and 325 days; 32 rats died and 225 rats were killed when they were moribund. Postmortem examinations on the 1080 rats revealed 38 spinal cord tumors, 191 spinal nerve tumors, 232 cranial nerve tumors, and 823 brain tumors. A methodical study of the tumor characteristics disclosed no evidence that exposure to the pulsed RF signal affected the incidence, malignancy, volume, multiplicity, latency or fatality associated with any kind of neurogenic tumor.     

Effects of extremely low frequency magnetic field on fertility of adult male and female rats.

To investigate the effects of an extremely low-frequency (ELF) magnetic field on their fertility, adult male and female Sprague-Dawley rats were exposed to a 50 Hz sinusoidal magnetic field of approximately 25 microT (rms) for 90 days before they were mated with unexposed counterparts. Exposure to a 50 Hz field reduced male rat fertility. The number of pregnant females was reduced when mated with exposed males, and the number of resorptions increased. The effects of magnetic field on male fertility were shown to be partly reversible, when the same exposed group of males were remated 45 and 90 days after being removed from the fields. Exposure of adult female rats to 50 Hz magnetic fields for 90 days before mating significantly reduced their fertility. The mean numbers of implantations and living fetuses per litter were statistically significantly decreased in the 50 Hz group. These results suggest that low frequency magnetic fields have some adverse effects on fertility of male and female rats.     

Cytogenetic effects of microwave irradiation on male germ cells of the mouse

Hybrid male mice were exposed to 2.45 GHz microwaves for 30 min/day, 6 days a week for two consecutive weeks at power densities of 1.0, 100 or 400 W m-2, with sham-exposed controls. Rectal temperatures before and after exposure were measured on days 1, 6 and 12. Measurements made on day 1 were treated with caution because of heterogeneity in rectal temperatures taken before exposure between the groups of mice given different treatments. On days 6 and 12, rectal temperatures rose by approximately 1 degree C in mice sham exposed, or exposed to 1 W m-2 or 100 W m-2. Only in the group of mice exposed to 400 W m-2 was the mean rise in rectal temperature during exposure (about 3 degrees C) significantly increased above the sham value. In groups killed 2-3 days after treatment (mainly meiotic exposure) frequencies of chromosome aberrations in spermatocytes showed no significant heterogeneity although the highest frequency of 1.5 per cent was at the highest (400 W m-2) power density. Another group killed 30 days after 100 W m-2 exposures (spermatogonial sampling) showed no significant increase over controls in chromosome aberration frequency. There was a small but significant increase in sperm count with increasing power density in mice killed 12-13 days after exposure, but a non-significant one in those exposed as spermatogonia (killed 41 days later). Thus effects were markedly less severe than those reported previously by Manikowska-Czerska et al. (1985) with a very similar radiation regime and were probably caused by the temperature enhancement.     

Age-dependent expression of cytochrome P-450s in rat liver

Age-related changes in the levels of multiple forms of cytochrome P-450 as well as in the testosterone hydroxylation activities of hepatic microsomes of male and female rats of different ages from 1 week to 104 weeks (24 months) were investigated. The total cytochrome P-450 measured photometrically did not change much with age in either male and female rats. Testosterone 2 alpha-, 2 beta-, 6 beta-, 15 alpha-, 16 beta-hydroxylation activities of male rats were much higher than those in female rats and were induced developmentally. These activities in male rats declined with aging to the very low level in female rats by 104 weeks of age. Testosterone 7 alpha-hydroxylation activity was maximum at 3 weeks of age in rats of both sexes. The levels of individual cytochrome P-450s were measured by immunoblotting. P450IA1 and IA2 (3-methylcholanthrene-inducible forms) and P450IIB1 and IIB2 (phenobarbital-inducible forms) were detected at low levels in rats of both sexes at all ages. P450IIA2, IIC11 and IVA2 were detected in male rats only and were induced developmentally. These male-specific forms disappeared in male rat liver at 104 weeks of age. P450IIC12, a typical female-specific form, was induced developmentally in female rats and was also detected in male rats at 3 and 104 weeks of age. P450IIIA2 (testosterone 6 beta-hydroxylase) was induced developmentally in male rats, but disappeared when the rats were 104 weeks of age. In female rats, P450IIIA2 was detected only at 1 and 3 weeks of age. P450IIA1, IIC6, IIE1 and IVA3 were detected in rats of both sexes at any age. P450IIC6 and IVA3 were induced developmentally and detected at a similar level in rats of both sexes. The level of P450IIA1 was maximum at 3 weeks of age in rats of both sexes. The changes in the level of P450IIE1 during aging were small compared with the changes in other cytochrome P-450s used in this study. These observations provide concrete evidence to our earlier hypothesis that each of the forms of cytochrome P-450 in male rats alter with aging in different patterns resulting in a practical feminization of over-all cytochrome P-450 composition at old age.     

高脂饮食联合光照周期改变对不同性别小鼠体重的影响

摘要 目的：随着夜间光照与肥胖现象日趋普遍化,机体内的昼夜节律与生理代谢均受到不同程度的影响,其中不同性别间的差异有待进一步研究。本文旨在通过比较高脂饲料喂养,以及改变光照周期从而对不同性别小鼠体重产生的影响来模拟高脂肪饮食时人类受到夜间光照的性别差异。方法：随机选取C57BL/6小鼠雌鼠、雄鼠各12只,分别按照性别、喂养饲料随机均分成4组,其中随机选取一组雌鼠和一组雄鼠喂养60%高脂饲料作为实验组,另外的一组雌鼠和一组雄鼠喂养普通饲料作为对照组,连续喂养8周,观察并记录各组小鼠体重变化;第1~6周将实验小鼠置于24h/0h光照周期下生活,第6~8周实验小鼠生活的光照周期改为12h/12h。结果：在高脂饲料喂养以及光照周期失调（24h/0h）的条件下,雌、雄鼠体重均有增长（P<0.05）,但雄鼠体重增加量是雌鼠的三倍。当光照周期恢复正常（12h/12h）后,雌、雄小鼠体重增长量均下降。不同性别的小鼠食用高脂饲料以及生物节律被打乱时体重均增加,但雄鼠体重增加量明显大于雌鼠,提示同在高脂饲料饮食的条件下,雌鼠受生物节律影响比雄鼠更大。结论：高脂饮食实验小鼠模型中雌鼠受生物节律的影响比雄鼠更大。     

Activation of antitumor properties in alveolar macrophages from protein-calorie malnourished rats

Summary Protein-calorie malnutrition (PCM) was induced by feeding male F344 rats on a 5% casein diet for 7 weeks. At appropriate times, rats from control (20% casein diet) and PCM groups were killed and alveolar macrophages (AM) were obtained by bronchoalveolar lavage. The functional integrity of the AM was determined by measuring their ability to become tumoricidal on treatment with macrophage activators, such as muramyl dipeptide (MDP) or multilamellar liposomes containing MDP or its lipophilic analog, MTP-PE. After 5 and 7 weeks, the numbers of lavaged AM per gram body weight of rats were much higher in the PCM group than in the control group. In week 3, AM from the PCM group showed spontaneous tumoricidal activity against syngeneic tumor cells, but in weeks 5 and 7 they did not. However, AM from PCM rats behaved the same way as controls in their response to activation stimuli in vitro with multilamellar liposomes containing synthetic MDP or MTP-PE.These data show that PCM affects the number of AM, but that AM from rats in a state of PCM become tumoricidal in response to activation stimuli in vitro.     

Age-dependent exression of cytochrome P-450s in rat liver

Age-related changes in the levels of multiple forms of cytochrome P-450 as well as in the testosterone hydroxylation activities of hepatic microsomes of male and female rats of different ages from 1 week to 104 weeks (24 months) were investigated. The total cytochrome P-450 measured photometrically did not change much with age in either male and female rats. Testosterone 2α-, 2β-, 15α-, 16α-, and 16β-hydroxylation activities of male rats were much higher than those in female rats and were induced developmentally. These activities in male rats declined with aging to the very low level in female rats by 104 weeks of age. Testosterone 7α-hydroxylation activity was maximum at 3 weeks of age in rats of both sexes. The levels of individual cytochrome P-450s were measured by immunoblotting. P450IA1 and IA2 (3-methylcholanthrene-inducible forms) and P450IIB1 and IIB2 (phenobarbital-inducible form) were detected at low levels in rats of both sexes at all ages. P450IIA2, IIC11 and IVA2 were detected in male rats only and were induced developmentally. These male-specific forms disappeared in male rat liver at 104 weeks of age. P450IIC12, a typical female-specific form, was induced developmentally in female rats and was also detected in male rats at 3 and 104 weeks of age. P450IIIA2 (testosterone 6β-hydroxylase) was induced developmentally in male rats, but disappeared when the rats were 104 weeks of age. In female rats, P450IIIA2 was detected only at 1 and 3 weeks of age. P450IIA1, IIC6, IIE1 and IVA3 were detected in rats of both sexes at any age. P450IIC6 and IVA3 were induced developmentally and detected at a similar level in rats of both sexes. The level of P450IIA1 was maximum at 3 weeks of age in rats of both sexes. The changes in the level of P450IIE1 during aging were small compared with the changes in other cytochrome P-450s used in this study. These observations provide concrete evidence to our earlier hypothesis that each of the forms of cytochrome P-450 in male rats alter with aging in different patterns resulting in a practical feminization of over-all cytochrome P-450 composition at old age.     

Effects of 2450 MHz microwave radiation during the gestational period on the postnatal hematology of rats

Pregnant Sprague-Dawley rats were exposed to 2.45 GHz CW radiation for 3 h daily from day 4 through day 20 of pregnancy at an average power density of 10.3 mW/cm2. At 2, 10, 20, and 30 d postpartum, several aspects of peripheral blood hematology of male and female pups were examined. No effects were noted on pregnancy rate or litter size; however, pup weight was reduced. Also, the white blood cell numbers were lower in male and female pups exposed to microwave radiation and the differential cell counts were altered in the female pups at 10 d postpartum. At 30 d of age, no differences were noted between the sham and exposed pups for any of the hematologic variables examined.